The Incredible Surge of Black Rapids Glacier

Black Rapids Glacier is a picturesque valley glacier that flows out of the beautiful Alaska Range in interior Alaska. Like many glaciers, Black Rapids Glacier has experienced periods where it rapidly advances, called a surge. For most glaciers, this means a slight to moderate increase in the rate it flows. For Black Rapids Glacier, this meant advancing three miles in a three month period in the winter of 1937. Columbia Glacier, also located in Alaska, is a tidewater glacier which is continually moving into the ocean. During its surges, it moves at approximately 65 ft per day. Another Alaskan glacier is the Hubbard Glacier, which famously surged in 1986, advanced at a rate of 32 feet per day and dammed a fjord near a small village. According to Ernest N. Patty, a geologist at the time of the surge, Black Rapids Glacier advanced at approximately 220 feet per day!

Though Alaska is vast, the Black Rapids Glacier's surge of 1937 could have had catastrophic effects. The 27 mile long glacier terminates within a few miles of the Richardson Highway, which in 1937 was the only road connecting Alaska's two biggest cities, Anchorage and Fairbanks. Thankfully, the glacier slowed down and began retreating before it crossed the highway. Had it continued forward, the Black Rapids Glacier would also have surged past the Delta River, effectively damming it. Sediments around the river match those of the terminal moraine of Black Rapids Glacier, indicating it may have surged past the Delta River sometime ago.

Today, Black Rapids Glacier is still retreating. Could it surge again? Scientists think so, as surges are one of the natural phases a glacier can pass through. Though Richardson Highway is no longer the only link between Fairbanks and Anchorage, the potential damming of the Delta River could pose grave danger to the nearby Black Rapids Lodge and community of Delta Junction. Another potential problem is the proximity of the Trans-Alaska pipeline, which was built in the 1970's and passes through between the glacier and the river. Thankfully, engineers took the glacier's history into account and created safety measures that will keep the pipeline and surrounding ecosystem safe in the event of a surge.

The incredible surge of Black Rapids Glacier in 1937 demonstrates how glaciers are dynamic and an interactive part of our environment. Think of Black Rapids Glacier next time you feel like telling a slowly moving friend they are moving at glacial speed- they may take that as a compliment!

Sources:

http://ak.water.usgs.gov/glaciology/black_rapids/index.htm

http://www.gi.alaska.edu/ScienceForum/ASF13/1342.html

http://www.time.com/time/magazine/article/0,9171,757342-1,00.html